The present invention relates to a connector used for surface mounting on a circuit substrate in an electronic device, particularly relates to a connector having a plunger resiliently urged by a spring so that the upper end of the connector may press terminal electrodes of electric parts to be electrically connected to the circuit substrate in the electronic device.
In an electronic device such as a portable telephone, a portable computer, and a game console, there are provided spring connectors for connecting battery, acoustic parts, peripheral circuits and other electric parts to a circuit substrate of the electronic device. Japanese Patent Application Laid-Open 2002-25657 discloses on page 3 and in FIG. 2(D), one of these spring connectors. The spring connector has a plunger which is slidably mounted in a tube and outwardly urged by a spring. The spring connector is secured to a circuit substrate and the plunger is pressed against a terminal electrode of the electric part in assembling process of the part in the device, thereby electrically connecting the part to the circuit substrate.
FIGS. 2 and 3 show similar conventional spring connectors.
Referring to FIG. 2, the spring connector comprises a cylindrical tube 11 made of metal, and a metal plunger 13 slidably inserted in the tube 11 and outwardly urged by a coil spring 12. A shoulder 13c of a flange 13a of the plunger 13 is pressed against a bent edge 11a of the tube 11 by the coil spring 12 so as not to slide out of the tube 11. The outer surfaces of the tube 11 and the plunger 13 are covered by nickel and gold plating. Both the tube 11 and the plunger 13 are formed by cutting work.
FIG. 3 shows another conventional spring connector provided with a plunger 13A. The plunger 13A has the flange 13a, an underside 13d of which is inclined so that the peripheral wall of the flange is pressed against the inner surface of the tube 11 in an inclined condition. Thus the flange is strongly pressed against the inner surface, thereby ensuring the electrical conductivity between the tube and the plunger. In the present spring connector, the plunger 13A is formed using a header instead of by cutting so that the manufacturing cost is decreased. The header is a processing machine to press or squash a metal material to form into a predetermined shape.
In each of the above described spring connectors, there is a problem of dirt entering the tube. Accordingly, the contact resistance between the plunger and the spring is unstable. Particularly in the case of the spring connector of FIG. 2, since the underside of the plunger is not inclined, the contact resistance is even more unstable. Moreover, although the plunger is formed with header in the spring connector of FIG. 3, since the tube must be manufactured by cutting in both cases, the manufacturing cost cannot be sufficiently decreased.